Abstract
<jats:p>Ultrashort dual pulses of femtosecond duration with tunable wavelength and temporal separation are of significant interest for a wide range of scientific and technological applications, including pump–probe spectroscopy. Typically, such pulses are generated by splitting, delaying, and recombining a single ultrafast laser or by combining two independent ultrafast lasers at different wavelengths. However, these approaches suffer from intrinsic path-induced instability, increased complexity, and limited flexibility. Here, we demonstrate a single experimental scheme that overcomes these limitations, enabling the generation of dual ultrashort pulses within a single beam, offering flexible control over polarization, wavelength, temporal separation, and repetition rate. Using two 50-mm-long multi-grating MgO-doped periodically poled lithium niobate crystals in a singly-resonant optical parametric oscillator, independently pumped by a single ultrafast Yb-fiber laser at 1040 nm, we generate dual-pulse outputs in a single beam. The output pulses can possess identical or orthogonal polarizations, with repetition rates up to 100 GHz, temporal separation tunable up to the pump repetition period, and flexible wavelength separation in the near-infrared region. This novel system configuration provides a compact and versatile platform for ultrafast studies across the visible to mid-infrared spectral range, with particular advantages for polarization-resolved and wavelength-sensitive pump–probe measurements.</jats:p>